For estate and letting agents

For estate and letting agents: the twelve answers you send four hundred times

Is it still available. Can I view Thursday. What is the deposit. When do the referencing results come back. The boiler is making that noise again. Every enquiry arrives as a paragraph, every viewing generates three more emails, and by Friday you have written the same twelve answers more times than you care to count.

MailTwin does that part. You type the points the reply has to make, and it writes the finished email, in your own words.

What that looks like on a Tuesday

Select the message in Apple Mail, type the points your answer needs to make, and MailTwin writes the complete email into the reply window — greeting, every point in full sentences, sign-off. You read it, change what you want, and send it.

You type	You get
still available yes, viewing Thursday 2pm, photo ID on the day, parking round the back	The reply to the applicant confirming availability and the time, with what to bring and where to park spelled out
referencing back Friday, deposit five weeks' rent, holding fee comes off the first month	A tenancy email giving the timescale and both figures plainly, so they do not have to ask twice
boiler visit Tuesday morning, contractor rings first, tenant needs to be in	The maintenance update to the landlord, with the appointment and what is expected of the tenant
offer of 285 turned down, vendor holding at 295, would move on completion	The reply to the buyer with the vendor's position on price and where there is room to move

The point is not that any one of those is hard. It is that you write forty of them a week, and you write them at eight in the evening.

Two audiences, one inbox

You do not write to a landlord the way you write to an applicant, and the vendor who has had one viewing in six weeks needs a different register again. Most email tools give you a tone slider for that. MailTwin does something more useful: it learns voice separately for every mail account, from that account's own sent mail.

So if Apple Mail carries a lettings address and a sales address, MailTwin builds two voices from two sets of sent mail, and switching mailbox switches the voice. Nothing is shared between them. If everything goes out of one address you get one voice, and you steer the individual reply by what you type.

The rest of it

A chain about one flat can run to thirty messages by the time the tenancy starts. MailTwin summarizes the thread and pulls out the action items, which earns its keep on the Monday a colleague hands you an instruction mid-flight. It translates, for overseas landlords and applicants. And it will improve a draft you have already written, including inside Mail's own compose window.

Numbers you cannot get wrong

Deposits, rents, completion dates, the address of the property. A validator sits between the AI and your draft and rejects any rewrite that has changed a number, a date, an amount, a link or an email address. That is a real guard and it runs every time.

What it cannot do, and this matters, is judge whether a new sentence is true. Type the wrong deposit figure and it will write the wrong figure out in a well-composed sentence. The draft is yours to read before it goes, and MailTwin never sends anything on its own.

The honest version of the time saving

Christopher Naas, who makes MailTwin, says it saves him an hour or more on a busy email day. That is his experience, not a promise about your Saturday, and anyone quoting a precise figure for an agency inbox is guessing. What is reliably true is where the time sits: not in the difficult email to the vendor about a price reduction, but in the twenty easy ones either side of it.

What it will not do

It will not read your inbox on its own, triage it, file it, or answer anybody without you. There is no autonomous mode and no scheduled sending. It does not connect to your CRM or to the portals, so it will never know a property has gone under offer unless you tell it. It is macOS 13 or later only, Apple Mail only, with no iPhone or iPad app, so it is a desk tool and not something for the car between viewings. It needs two macOS permissions on the first run, Automation for Mail and Accessibility, which is a few minutes of clicking in System Settings and cannot be automated away, because Apple does not let an app grant itself access to your mail. And if your replies are mostly one line, it will not help you much. This is built for the paragraph.

One thing it does not care about is who hosts the mail. It attaches to Apple Mail, so Microsoft 365, Exchange, Gmail, iCloud and plain IMAP accounts all work the same way.

Where the mail goes

MailTwin has no AI of its own. You choose one of eight engines and supply the key. Two of them, Apple Intelligence on macOS 26 or later and Ollama, run on the Mac itself, and with those the message is never transmitted at all. With a cloud provider, the request goes from your Mac straight to that provider, along with a short sample of your own sent mail so the reply sounds like you. Your voice index stays on the Mac. Nothing goes to MailTwin, because there is no MailTwin server and no MailTwin account for it to go to.

For the data protection answer you will eventually have to give: the sent mail your voice is built from is read and stored locally, under your own user account.

For accreditation bodies, franchises and agency networks

If you run a scheme or a network and want to look at this properly before your members hear about it, write to [email protected] and licences for the office will come back, no conditions and nothing expected in return. Endorsements are not asked for and not implied. MailTwin is made by Smilodon AS, a one-person company in Norway, and the person who answers that address writes the code.

Common questions

Does it know whether a property is still available?

No. MailTwin does not read your CRM, your portal feed or your availability list, and it will not look anything up. You tell it the answer in a few words and it writes the email around it. It only knows what you type and what is in the message you selected.

Can the lettings address and the sales address sound different?

Yes, if they are separate accounts in Apple Mail. Voice is learned separately for every mail account, from that account's own sent mail, so lettings and sales keep their own register and nothing is shared between them. If both go out of one address you get one voice, and you steer an individual reply by what you type.

Could it change a deposit figure or a viewing time?

A validator checks every rewrite before it reaches the draft and rejects changed numbers, dates, amounts, links and email addresses. What it cannot do is judge whether a new sentence is true, so a wrong figure you typed will come back written out neatly. Read it before you send. Nothing sends on its own.

Does applicant and landlord correspondence go to a third party?

That is your choice, out of eight AI engines. Apple Intelligence on macOS 26 or later, and Ollama, run on the Mac itself and transmit nothing. With a cloud provider the request goes from your Mac straight to that provider under your own key, with a short sample of your own sent mail for the voice. It never goes to MailTwin, because there is no MailTwin server and no MailTwin account.

What does it cost, and is it monthly?

The licence is one-time, with a 30-day full trial and no card to start, and there is a five-licence pack for an office. The engine is separate: Apple Intelligence and Ollama cost nothing, and a cloud provider bills you for what you use, usually a few cents a day at ordinary volumes. The app shows a running total.

Try it on a week of enquiries

Thirty days, every feature, no card. Enquiry season is the only honest test.

Download MailTwin →

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